Guide: Iso Grifo A3/L Series 1 (GL300 / GL365 / GL350)
Background
Having amassed a fortune from refrigeration units and other home appliances, Milanese industrialist Renzo Rivolta began to construct motorcycles following the conclusion of World War 2.
1952 saw Rivolta move into the automotive market with his Isetta micro car, a machine subsequently licensed to BMW.
As European economies began to flourish, Rivolta decided to add a high end auto maker to his portfolio of businesses. Accordingly, Iso Rivolta was established in early 1962 and Giotto Bizzarrini was brought on board to create the marque’s first model: the IR300 / IR340 four-seat Coupe.
Unlike Ferrari and Maserati, Renzo Rivolta opted to use a tuned American engine to power his new luxury Gran Turismo. It was draped in an elegant five window Coupe designed by Carrozzeria Bertone and kitted out with a luxuriously equipped cockpit that matched anything Iso’s domestic rivals had to offer.
With production of the IR300 / IR340 underway, Renzo Rivolta commissioned Bizzarrini to add a pair of sporty new models to the Iso line-up.
The resultant Grifo A3/L was conceived as an elegant Bertone-bodied Coupe with a pair of occasional rear seats. Two variants were offered: the GL300 and GL365, the names of which referenced their respective metric horsepower ratings.
The rakish Drogo-bodied Grifo A3/C was a pure two-seater that would spearhead Iso’s move into GT racing. Customers could order an A3/C in either full-fat Corsa or slightly toned down Strada trim depending on their requirements.
Prototypes of both the A3/L and A3/C were displayed at the Turin Motor Show in October 1963.
An A3/L Grifo Spyder (chassis 420002) was then displayed at the Geneva Motor Show in March 1964 but remained a one-off.
Production of the A3/C (which was constructed at the Bizzarrini Prototipo factory in Livorno) got underway almost immediately after its Turin debut.
Meanwhile, Iso concentrated on getting the A3/L ready which proved a more time consuming task considering the demanding nature of customers in the luxury GT sector. To this end, the original prototype (chassis 420001, top photo) underwent a rigourous test and development programme over the next few months. The first deliveries then took place in mid 1965.
Chassis
The A3/L Grifo was based on a platform chassis like the one used by the IR300 / IR340 but with 250mm cut from the wheelbase (2450mm as opposed to 2700mm). Both versions were fabricated from pressed sheet steel and stiffened with a massive central backbone and boxed side members.
Unequal length double wishbones were fitted up front while out back was a De Dion axle with twin trailing arms and a transverse Watt’s linkage. Coil sprung hydraulic shocks were fitted all round and an anti-roll bar was installed at the front.
The servo-assisted brake system employed 299mm diameter discs at the front and 305mm items at the rear (where they were mounted inboard of the differential).
6 x 15-inch cast alloy Campagnolo wheels were originally shod with Pirelli Cinturato tyres.
Like the IR300 / IR340, a massive 100-litre fuel tank was loocated under the boot floor.
Engine / Gearbox
To power the IR300 / IR340, Iso had secured a supply of L75 motors of the type fitted to the C3 Corvette from General Motors.
With the arrangement having proved satisfactory thus far, the same all-iron, small block 90° V8 was used for the A3/L Grifo. These engines utilised pushrod-operated overhead valves (two per cylinder) and wet-sump lubrication. Displacement was 5350cc thanks to a bore and stoke of 101.6mm and 82.55mm respectively.
Once landed in Italy, the engines were modified with an enlarged oil sump fashioned from ribbed light aluminium-alloy. A small diameter oil radiator and bigger water radiator were fitted as well.
Iso offered their now blueprinted engines in two states of tune.
The entry level GL300 retained a single Carter AFB double-barrel carburettor and ran a 10.5:1 compression ratio. Peak output was 295bhp at 5000rpm and 360lb-ft at 3200rpm.
The top-of-the-range GL365 featured a different camshaft and valve arrangement, mechanical instead of quieter hydraulic tappets, a single Holley four-barrel carburettor and an 11.0:1 compression ratio. In this configuration, peak output was 360bhp at 6200rpm and 360lb-ft at 4000rpm.
Transmission was through an all-synchromesh Borg Warner T-10 four-speed manual gearbox, a single-plate clutch and Salisbury rear axle with limited-slip differential.
Bodywork
To design and fabricate bodywork for the A3/L Grifo, Renzo Rvolta returned to Carrozzeria Bertone following the firm’s successful execution of the IR300 / IR340.
The handsome new model was styled by Giorgetto Giugiaro who created one of the 1960s most handsome Grand Tourers.
Twin headlights per side were housed within wide intake nostrils split by a vertical body coloured septum. Another shallow intake was located underneath the full width bumper.
Sharply creased front fenders dropped gently away to a hood that featured a discrete power bulge. The fastback cabin featured slim A pillars and an expansive wraparound rear screen that afforded excellent visibility.
Distinctive slatted cooling vents were carved out from behind the front and rear wheels and the cockpit B-pillar. The sills were finished in a contrasting colour to the rest of the body to lend the car a slim side profile.
At the back was a body coloured full width aperture, single piece tail light clusters per side and another full width bumper.
Body panels were fabricated entirely from steel.
Interior
Inside, the A3/L Grifo’s cockpit was equipped to as high a standard as anything from Ferrari or Maserati.
Directly behind the wood-rimmed steering wheel with its three highly polished aluminium spokes were large read outs for engine and road speed with a small oil pressure gauge located in between. Outboard of these were more small readouts for oil temperature, fuel, water temperature and battery condition. In the centre of the veneered wood fascia was a clock. A radio was located in ahead of the passenger seat.
Well-padded front seats were given fluted centres and they tilted forward to enable access to a pair of useful storage cavities or a simple bench-type rear seat.
More fluting was used for the door panels, sills and rear seat inserts.
Upholstery was a mix of fine leather and carpet with perforated vinyl leatherette used for the headliner.
Electric windows were fitted as standard.
Options
In addition to the choice or rear seats or storage bins, buyers could specify Borrani wire wheels and a three-speed automatic gearbox.
Weight / Performance
Both versions of the A3/L Grifo weighed in at 1450kg.
The range-topping GL365 had a top speed of 161mph and 0-62mph time of 6.1 seconds.
The entry level GL300 had a top speed of 146mph and 0-62mph time of 6.4 seconds.
Renzo Rivolta & Giotto Bizzarrini Split
Soon after production of the A3/L Grifo was underway, Renzo Rivolta and Giotto Bizzarrini terminated their cooperation agreement.
Although the A3/C had shown much promise during its 18 month competition career, the car had been developed, marketed and raced entirely at Renzo Rivolta’s expense. However, Giotto Bizzarrini had supplied nearly every A3/C with a Bizzarrini badge and most of the car’s competition outings had been made under Bizzarrini Prototipo entries. Inexplicably, it also transpired the Giotto Bizzarrini had registered the Grifo trademark for himself.
At the end of August 1965, an exasperated Renzo Rivolta ended his association with Bizzarrini.
In exchange for the Grifo trademark, Bizzarrini was given sole production rights to the A3/C and enough component parts to construct 50 cars under whatever name he desired.
Death of Renzo Rivolta
Unfortunately, on August 19th 1966, Renzo Rivolta unexpectedly died of a heart attack. He was 57 years old.
The company was taken over by his 25-year old son, Piero, who had graduated from university with a doctorate in mechanical engineering.
A3/L Grifo Targa & New Options for 1967
At the Turin Motor Show in October 1966, Iso unveiled a new A3/L Grifo with a full width removable Targa roof panel. The prototype also featured a removable plastic rear window but most cars came with conventional glass panels.
Around the same time, a number of new options were introduced for 1967 to include a five-speed manual ZF gearbox, power steering (also sourced from ZF), air-conditioning and a two-piece sunroof.
As a result of a new hydraulic lifter, the GL365 engine was downgraded to 350bhp at 5000rpm and 380lb-ft at 3200rpm.
A3/L Grifo 7 Litri
Iso went on to introduce an A3/L Grifo 7-litri at the Geneva Motor Show in March 1968. Production of these monstrously powerful variants (covered separately) began towards the end of the year.
End of Production
Production of the first series A3/L Grifo was discontinued towards the end of 1970 – a Series 2 version (covered separately) which featured partially concealed headlights and Ford instead of Chevrolet power was unveiled at the Turin Motor Show that October.
In total, 330 examples of the first generation A3/L Grifo were completed of which 265 were to GL300 / GL365 / GL350 trim with the remaining 65 having been 7-litri variants.
Text copyright: Supercar Nostalgia
Photo copyright: Iso
